What is shadow zone of earthquake?
What is shadow zone of earthquake?
The shadow zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves. The shadow zone results from S waves being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core.
Why do shadow zones create earthquakes?
The earthquake waves develop shadow zones because: (i)The P and S waves follow a curved path in the interior of the earth which proves that the density increases inside the earth. (iii)On reaching the core ‘S’ waves disappear and P waves are refracted as a result there is no wave for a distance.
Why do earthquakes develop shadow zone 11?
(iii) Earthquake waves develop shadow zones because of the properties of each (P and S) waves as well as the core. Outer crust is liquid and hence S-waves, which can travel only through solid material, is blocked and cannot move across the core.
What depth is the shadow zone?
“What we have found is that at around 2 kilometres (1.2 miles) below the surface of the Indian and Pacific Oceans there is a ‘shadow zone’ with barely any vertical movement that suspends ocean water in an area for centuries,” says oceanographer Casimir de Lavergne from the University of New South Wales in Australia.
What is Rayleigh and Love waves?
Love waves have a horizontal motion that moves the surface from side to side perpendicular to the direction the wave is traveling. Of the two surface waves, Love waves move faster. Rayleigh waves cause the ground to shake in an elliptical pattern. This motion is similar to that observed in ocean waves.
What is a shadow zone Why is it developed?
Shadowzones are produced on the other sides of the planet due to waves being refracted or blocked by the liquid outer core of Earth. When earthquakes occur, they produce primary and secondary waves (called compression and shear waves sometimes).
Why do earthquakes appear?
Earthquakes are usually caused when underground rock suddenly breaks and there is rapid motion along a fault. This sudden release of energy causes the seismic waves that make the ground shake. The earthquake starts at the focus, with slip continuing along the fault. The earthquake is over when the fault stops moving.
What is shadow zone class11?
The direction of vibrations of S-waves is perpendicular to the wave direction in the vertical plane. Hence, they create troughs and crests in the material through which they pass. Thus, a zone between 105° and 145° from epicentre was identified as the shadow zone for both the types of waves.
What is earthquake wave 11?
Answer. 87.3k+ views. Hint: The energy and vibration that travels through earth’s layers when an earthquake , volcano or other explosion occurs, is called seismic wave. These waves travel through different layers of earth. As different layers have different densities, these waves get reflected and refracted.
How do geologists know the location of an earthquake?
Geologists use seismic waves to locate an earthquake’s epicenter, measuring the difference between the arrival times of the P waves and S waves.
What is the frequency of Rayleigh wave?
Rayleigh waves propagating at high ultrasonic frequencies (10–1000 MHz) are used widely in different electronic devices. In addition to Rayleigh waves, some other types of surface acoustic waves (SAW), e.g. Love waves, are also used for this purpose.
What is a shadow zone during an earthquake?
Shadow zone. Part of a series on. A seismic shadow zone is an area of the Earth’s surface where seismographs can only barely detect an earthquake after its seismic waves have passed through the Earth. When an earthquake occurs, seismic waves radiate out spherically from the earthquake’s focus.
What causes an earthquake’s shadow zone?
What causes an S-wave shadow zone is the fact that S-waves cannot go through liquids, only solids. Since the outer core is liquid, the S-waves are forced to stop, creating a shadow zone on the other side of the earth from where the earthquake happened.
What is P wave shadow zone?
The P-wave shadow zone is the area inside the earth where p waves can’t travel through because of refraction of seismic waves in the mantle and core.
